There are only 5 billion essentially distinct Sudoku puzzles (solutions) (proof here using Group Theory and Burnside's Lemma).

Interesting article on rating the difficulty of Sudoku's and various solving methods (including a short backtracking program written in Ruby).

Really interesting problem in recreational mathematics - try to reverse a unit line segment via translations/rotations - but in doing so sweep out a minimal area.

PI/4 is the obvious minimum - but it turns out you can do so in an arbitrarily small area.

What's odd to me, is that any combinations of moves that are either a) rotations about the center and b) translations, CAN NOT achieve an area less than PI/4; so it's counter-intuitive that you can do better than that.

Like the MIT physics simulator - a game played by drawing physical objects to solve a series of puzzles. Best played with a tablet.

What kind of hutzpah do you have to have to release "Scrabulous" which is a direct rip-off of Scrabble (same tile distribution, same board layout, same dictionary).

I don't know which of these components are are protected by copyright law - it seems reasonable to me that Scrabulous has violated not only copyright but also the trade mark of Hasbro.

Hasbro cannot protect the "idea" of an anagramming word game. This is an opening to create a "open source game design". We just need a group to create the following components and license under an open source license:

- Board design
- Tile distribution
- Word list
- Scoring rules

I recently did an analysis of the tile distribution of Scrabble as compared to a standard corpus of English words. I found these major differences. Of the 98 tiles in Scrabble, it has:

- Too few H's (should have 6 instead of 2).
- Too many I's (should have 7 instead of 9).
- Too few S's (should have 6 instead of 4).
- Too few T's (should have 9 instead of 6).

It would take a very rare solver to get through Saturday's NYT crossword w/o assistance. This blog post illustrates that virtually all were stumped by it (I got 4 clues and quit - my mom toughed it out with help from me confirming or rejecting her guesses from the solution).

Biographical article about the maker of the Saturday NYT crossword this week - one of the most diabolical in recent memory.

Quoted: Crossword maker Bob Klahn is a puzzling character

Our friends told us about this really fun anagramming game, so I snapped one up when I saw it for sale today. There are 144 letter tiles. Each person races to complete a valid Scrabble-style crossword with his own letters.

After we played I checked the letter distribution. Interestingly, they are long on a few letters (from what you'd expect in normal English letter distribution: two each of JQXZ (expect 0), and they are really short on H's: 3 included (expect 9).

Cute domain name.